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The on-board production of oxygen is demanded for future long-term missions such as International Space Station, Lunar base and missions to Mars. The needed oxygen can be recovered by electrolysing the water produced by the carbon dioxide processing system or other on-board water sources like water condensate. This way the oxygen loop will be closed. Since 1985 in a harmonised programme sponsored by the European Space Agency (ESA) and the German Space Agency (DARA), the required technology for an air revitalisation system (ARS) is being developed. The system is based on carbon dioxide concentration using solid amine water steam desorption, carbon dioxide hydrogenation (Sabatier) and fixed alkaline electrolysis. This paper reports on the manufacturing and testing of the fixed alkaline electrolyser (FAE) system designed for a 3-person capability and it discusses the current status of the ARS.

An advanced trace gas monitoring system for long duration manned space missions - such as the International Space Station - is discussed. The system proposed is a combination of a Fourier-Transform Infrared Spectrometer (FTIR) and a distributed ‘Smart Gas Sensor system (SGS). In a running multi-phase programme [1,2] the FTIR technology, applying novel analysis methods, has been demonstrated to handle multi-component gas measurements, including identification and quantification of 20 important trace gases in a mixture. In the current phase 3, initiated end of 1997, a fully operational FTIR technology demonstration model will be manufactured and tested. The SGS consists of an array of twenty electrically conductive polymer sensors supplemented with an array of quartz crystal microbalance sensors. The technology has been tested on the Russian MIR space station and is currently miniaturized into a second-generation flight model.

The longer human beings in closed habitats need to be supplied with life support functions, the more the closure of the ECLSS loops becomes a must. This is certainly valid for habitats in space, where a steady resupply of consumables from Earth is impossible due to excessive distances or prohibitive high cost, but it may apply in general to earthbound habitats as well, if for instance large submarines want to extend their diving time. In two harmonised programs for the two customers European and German Space Agency (ESA/ESTEC, DARA), Dornier is now in charge with the development of the technologies for the closure of the oxygen loop.

The development of the air revitalisation system ( AR) for a crewed spacecraft was initiated in 1985. The selected technical approach is a three-step process consisting of (1) a solid amine water steam desorption system to concentrate (the mainly) metabolically produced carbon dioxide(CO2) from the air (2) a Sabatier reactor to reduce the CO2 to water and methane (CH4) and (3) a fixed alkaline electrolyser to reclaim from the water the oxygen O2 for the crew. During 1996 / 1997 the AR system was successfully demonstrated on a laboratory scale configuration for a crew of three persons equivalent. During 1998 / 2000 the AR system was transformed into a rack-mounted so-called Air Revitalisation System Technology Demonstrator (ARSD) for ‘closed loop’ testing in a dedicated Closed Chamber, to demonstrate the readiness of the technology for a possible incorporation in the ISS enhancement programme.

Since 1985 in a step by step approach an advanced air revitalisation system has been developed for a crewed spacecraft. The metabolically produced carbon dioxide is concentrated through a solid amine water steam desorp-tion system and reduced to water and methane in a so-called Sabatier reactor. The water is currently fed into a fixed alkaline electrolyser to reclaim the oxygen for the crew. However, also water from other sources may be used. The hydrogen is recycled into the Sabatier reactor. The present system handles methane as a waste product closing so far the oxygen loop only. The system has been already successfully demonstrated in a laboratory scale configuration for a crew of three persons in 1996/1997. This paper discusses the results of the current development phase in which the system is reconfigured to fit into an International Space Station payload rack (ISPR). For this purpose the complete system design has been reviewed and upgraded where necessary.